Placenta accreta spectrum into the parametrium, morbidity differences between upper and lower location.

OBJECTIVE

To demonstrate the surgical and morbidity differences between upper and lower parametrial placenta invasion (PPI).

MATERIALS AND METHODS

Forty patients with placenta accreta spectrum (PAS) into the parametrium underwent surgery between 2015 and 2020. Based on the peritoneal reflection, the study compared two types of parametrial placental invasion (PPI), upper or lower. Surgical approach to PAS follows a conservative-resective method. Before delivery, surgical staging by pelvic fascia dissection established a final diagnosis of placental invasion. In upper PPI cases, the team attempted to repair the uterus after resecting all invaded tissues or performing a hysterectomy. In cases of lower PPI, experts performed a hysterectomy in all cases. The team only used proximal vascular (aortic occlusion) control in cases of lower PPI. Surgical dissection for lower PPI started finding the ureter in the pararectal space, ligating all the tissues (placenta and newly formed vessels) to create a tunnel to release the ureter from the placenta and placenta suppletory vessels. Overall, at least three pieces of the invaded area were sent for histological analysis.

RESULTS

Forty patients with PPI were included, 13 in the upper parametrium and 27 in the lower parametrium. MRI indicated PPI in 33/40 patients; in three, the diagnosis was presumed by ultrasound or medical background. The intrasurgical staging categorizes 13 cases of PPI performed and finds diagnosis in seven undetected cases. The expertise team completed a total hysterectomy in 2/13 upper PPI cases and all lower PPI cases (27/27). Hysterectomies in the upper PPI group were performed by extensive damage of the lateral uterine wall or with a tube compromise. Ureteral injury ensued in six cases, corresponding to cases without catheterization or incomplete ureteral identification. All aortic vascular proximal control (aortic balloon, internal aortic compression, or aortic loop) was efficient for controlling bleeding; in contrast, ligature of the internal iliac artery resulted in a useless procedure, resulting in uncontrollable bleeding and maternal death (2/27). All patients had antecedents of placental removal, abortion, curettage after a cesarean section, or repeated D&C.

CONCLUSIONS

Lower PAS parametrial involvement is uncommon but associated with elevated maternal morbidity. Upper and lower PPI has different surgical risks and technical approaches; consequently, an accurate diagnosis is needed. The clinical background of manual placental removal, abortion, and curettage after a cesarean or repeated D&C could be ideally studied to diagnose a possible PPI. For patients with high-risk antecedents or unsure ultrasound, a T2 weight MRI is always recommended. Performing comprehensive surgical staging in PAS allows the efficient diagnosis of PPI before using some procedures.